Absorbers for converting the sun's radiant energy into heat which is then transferred to liquids and employed for useful purposes are old in the art. Such apparatus, however, include a number of objectionable features. First, the cost of installation is quite high and second, these systems are heavy and complicated. Where the working substance is air or a gas, the air is circulated across the surface absorbing the radiant energy from the sun in an enclosure having glass or plastic windows to take advantage of the so called "greenhouse effect". On a cold day, a very substantial amount of heat may be lost by such structures through the windows as a result of contact of the air with the said glass or plastic surfaces. The air passing through the absorber on a cold sunny day may thus actually undergo a drop in temperature. The conventional way of reducing this heat loss is to use double or triple windows having air spaces therebetween. Such installations are expensive to install, expensive to keep clean, and have double or triple the energy loses due to absorption of the sun's rays by the glass.
A feature of the present invention is its means for heating a circulating stream of air or gas without bringing it into contact with ambient temperatures.
A further feature of the present invention is to employ a combination of a sheet material having corrugated surfaces to form the wall of the absorber conduit facing the energy source and a sheet having flat surfaces to form the opposite wall.
Another feature of the invention includes the use of a baffle to prevent warm air from contacting surfaces cooled by ambient air.
A feature of the invention is to use reinforced or roofing material for the absorbing units.
Additional details of the invention will be disclosed in the following description, taken in connection with the accompanying drawings, in which drawings, similar elements have been given identical reference numerals.